Genome Editing Technology
The most remarkable breakthrough in molecular biology!
Millions of people across the globe suffer from various types of cancers, heart and lung diseases. However, over the past few years, the recovery rate has immensely increased. Wondered how? Here’s your answer.
Genome editing technology involves a bunch of techniques that collectively have the ability to modify the DNA of an organism. This can be done by either insertion, deletion, modification, or replacement at a specific site within the DNA molecule.
1. Insertion — Using plasmids and vectors, we can carry out gene insertion. It basically means the addition of genes into the DNA sequence for studies of developmental biology in animals and plants. On insertion of new nucleotides, the amino acids that they code for may change and thus change the structure of the protein.
2. Deletion — Deleting a few nucleotides from a particular site in the DNA sequence.
Genome editing uses a set of four “engineered nucleases” in order to make cuts in the genome. The 4 families are:
1. Zinc Finger Nucleases (ZFN) — ZFN is a cleaving agent used for gene editing. It can be divided into two distinct regions.
a. A chain of two-finger modules that have the ability to recognize unique hexamers (sequences having 6 base pairs). The DNA binds to this part to continue the process.
b. A nuclease region where the DNA is cleaved.
When these two regions are put together, binding and cleaving of DNA can be carried out effectively. It is used for repairing mutations, disable or edit an allele, etc.
2. Transcription-Activator Like Effector-based Nucleases (TALEN) — These nucleases take part in the synthesis of the C terminal which in turn produce heterodimers for the formation of Double-Stranded Breaks. This too has a DNA-binding region made up of TAL effector and a catalytic region that participates in DNA cleaving.
3. Meganucleases — These are also called Homing Endonucleases and have characteristic long recognition sequences of 12 to 40 base pairs. These possess the ability to remove, replace or change the targeted sequence. Due to better DNA sequence recognition, it causes less toxicity in cells as compared to ZFN, however, the enzyme construction process can be time-consuming and expensive.
4. Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) — This enzyme plays the role of molecular scissors. It contains an RNA molecule that allows complementary base pairing to specific regions on the DNA strand. The Cas9 CRISPR technique allows the eukaryotic genome to be cut at any sequence when inserted into the genome. It can be divided into 3 distinct components: Protospacer Adjacent Motif (PAM), crRNA, and trans-activating crRNA.
The development of genome editing technology has paved the way for the successful treatment of various diseases and improvement of the quality of plant products. Here are some research models that have shown positive results in the recent past.
1. Genome editing — In the ex-vivo method, the cells isolated from the patients are extracted and undergo gene editing using the nucleases. They then undergo autologous transplantation before they can be injected back into the patient. In the in-vivo method, on the other hand, viral and non-viral vectors that contain the therapeutic drug are injected into the patient with the disease.
2. Cancer treatment — over the past few years, research has shown that TALEN can be used as a tool to study the molecular aspects of genetic mutations. It can delete cancer-causing genes and thus can save patients suffering from prostate and breast cancer. Moreover, the CRISPR/Cas9 system is being studied to treat malignant cancers and replace the sequences with normal ones.
3. Other than this, it has also come up with therapies for other metabolic diseases like diabetes, cardiovascular diseases, Alzheimer’s, and genetic disorders. This is done by delivering several monoclonal antibodies, necessary proteins, or hormones.
4. This technology is also used in plants to modify genes in crops and boost the agricultural sector. Transgenic plants can be made to give a higher yield of better quality, with long shelf life. They can also be made disease, stress, and pest resistant. Some examples of transgenic crops are the Flavour Savour tomato, Golden rice, BT cotton, BT brinjal, and many more.
Genome editing technology can resolve a variety of issues like sustainability, health, economy, agriculture, and more. It is rightly said by Sir Isaac Asimov, “The advance of genetic engineering makes it quite conceivable that we will begin to design our own evolutionary progress.”
References:
https://medlineplus.gov/genetics/understanding/genomicresearch/genomeediting/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3267165/
https://www.yourgenome.org/facts/what-is-genome-editing
https://www.slideshare.net/VikasVerma268/genome-editing-techniques
https://jgeb.springeropen.com/articles/10.1186/s43141-020-00078-y
